In the past it has been found that whenever quantitative electrochemical measurements are performed it is necessary to have both a reproducible and accurately defined electrode area which is in contact with the sample being analysed. When performing a measurement in a bulk solution the usual practice has been either to have the electrode immersed to a certain level in the liquid or alternatively to have an insulation layer applied to the electrode to leave only a precisely defined area in contact with the solution. These practices have proved to be relatively expensive and unreliable. It has also been found that when these methods are used it is difficult to prevent leakage and contact with the electrode outside the defined area, especially when the substrate upon which the electrode is placed is porous.
The present invention seeks to overcome or at least ameliorate the problems of the prior art by providing a method which is inexpensive, simple to apply and reliable.